On the first test machine I used (which was well below what they recommended, it was slow as cold molasses.
On a 3 GHz, 1 gig RAM machine, I managed to get up to 176,000+ messages (over 2 .5 gig) and it wasn't that bad but still it was slow. As the mentioned in the video, performance is still being worked on. A lot of indexing going on.
Comparing the 117,000 messages in the current OE to the new format, I don't know how you can put 200,000 messages in OE as it is now and not be slower.
I can tell you that the messages I used for this test were put into an OE dbx file first then extracted with one of Steve Cochran's tools (I forget whethere I used DBXpress or OEX) and then burned that to a CD and did a drag and drop into Vista's build of OE.
This has been the only testing I have done in the newer Vista build of OE. Copying, deleting, moving messages and little of anything else. Bryan can tell you I have been rather vocal in the past about the stability of the message stores in OE. I am not the only one either. As to Community features, Word wheel or Contacts (which has been a pet peeve of mine as well), I have looked at those very little. Stability of the message stores has been a high priority with me.